Dear Matthew,
I have done several QPA for pharmaceutical formulars for QUT Health. One
example is: https://doi.org/10.1016/j.ijpharm.2020.119684
They were all measured using Debye-Scherrer geometry, becasue too much
penetration/absorption error in Bragg-Brentano.
Many APIs have particle sizes as big as 200 micron, good for SC-XRD but not
ready for PXRD.
So I always gently grind APIs in mortar and pestle for 1 min to reduce particle
aspect ratio, before loading into capillaries, therefore I seldom use/need PO
correction.
One thing below RR paper did not touched is about refining crystal structure
before QPA.
Many .cif structure in ICDD were solved using SC-XRD at lowT e.g. 100K.
I seldom get perfect fit using those .cif structure straight away, because when
the organic crystals were measured at RT, the molecules tend to stretch a
little.
So I always refine the API structure using Rigid Body model in TOPAS to achieve
good fit (a tiny molecule distorsion could reduce Rwp a lot), before using
these refined Rigid Body structure in QPA for mixtures data.
Hope my two cents help.
Best Regards!
--
Dr. Xiaodong (Tony) Wang
Senior Research Infrastructure Specialist (XRD)
Central Analytical Research Facility (CARF) | Queensland University of
Technology
Address: Level 6, P Block, Gardens Point campus, 2 George St Brisbane QLD 4000
Tel: +61 7 3138 1904 | Mob: 0452 571 680
Email: tony.w...@qut.edu.au | Web: www.qut.edu.au/ife/carf
At 2024-05-16 13:55:03, "Matthew Rowles" <rowle...@gmail.com> wrote:
Hi all
Are there any publications\guides on the specimen prep and data collection
regimes for pharmaceutical samples? Specifically for quantitative phase
analysis and phase ID.
I know of the ICDD pharma round robin (Powder Diffr., Vol. 25, No. 1, March
2010).
I'm a neophyte in this area, and am looking to avoid major pitfalls
Matthew
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